injectedScore

Set an initial score for newly injected pages. Note: newly injected pages
may have no inlinks, so filter implementations may wish to set this
score to a non-zero value, to give newly injected pages some initial
credit.

initialScore

Set an initial score for newly discovered pages. Note: newly discovered pages
have at least one inlink with its score contribution, so filter implementations
may choose to set initial score to zero (unknown value), and then the inlink
score contribution will set the "real" value of the new page.

doc - document. NOTE: this already contains all information collected
by indexing filters. Implementations may modify this instance, in order to store/remove
some information.

initScore - initial boost value for the Lucene document.

Returns:

boost value for the Lucene document. This value is passed as an argument
to the next scoring filter in chain. NOTE: implementations may also express
other scoring strategies by modifying Lucene document directly.